What Causes Concrete to Crack?
Updated: Aug 10
Understanding What's Normal and What Isn't
One of the biggest concerns homeowners have after a new driveway, patio, garage, or pole barn floor is poured is seeing a crack appear.
The good news is that not every crack is a sign that something went wrong.
Concrete is a durable building material, but it's also natural for it to shrink as it cures. Understanding why concrete cracks—and what steps help minimize cracking—can give you confidence in your investment. Concrete Naturally Shrinks
As concrete cures, excess water evaporates and the material shrinks slightly. This process creates internal stress that can lead to small cracks.
This is one reason concrete contractors install control joints. These joints encourage concrete to crack in predetermined locations rather than randomly across the slab. Improper Base Preparation
A stable, well-compacted base helps support the slab over time.
If the ground beneath the concrete settles or shifts, it can place additional stress on the slab and contribute to cracking.
Proper excavation, grading, and compaction are essential for long-term performance. Heavy Loads
Concrete should be designed for how it will be used.
Parking equipment or vehicles that exceed the slab's intended design can increase stress on the concrete and contribute to damage over time.
This is why slab thickness and reinforcement should be selected based on the project's intended use. Weather Conditions
Illinois experiences freezing temperatures, thaw cycles, heat, and moisture throughout the year.
These changing conditions cause concrete to expand and contract, which is one reason joints and proper installation techniques are so important. Reinforcement Helps—But Doesn't Eliminate Cracks
Rebar and fiber mesh help reinforce concrete, but neither prevents all cracking.
Reinforcement helps concrete perform as designed, while proper base preparation, quality finishing, curing, and control joints all contribute to long-term durability. How Contractors Help Reduce Cracking
Professional concrete contractors use a combination of techniques to help minimize cracking, including:
Proper site preparation
Quality concrete mixes
Correct slab thickness
Reinforcement when appropriate
Strategic control joint placement
Proper finishing
Proper curing practices
No concrete installation can be guaranteed to remain completely crack-free, but quality workmanship can help improve long-term performance. Is Every Crack a Problem?
Not necessarily.
Small hairline shrinkage cracks are common and are often cosmetic.
However, cracks that continue to widen, show significant vertical movement, or are accompanied by settlement may indicate a larger issue that should be evaluated by a qualified professional. Build It Right From the Start
The best way to reduce the risk of future concrete problems is to start with proper planning, quality materials, and experienced installation.
At Mawcrete Concrete, we focus on every step of the process—from site preparation to finishing—to help deliver durable driveways, patios, garages, pole barns, and commercial slabs throughout Central Illinois.
If you're planning a concrete project, contact Mawcrete today for a free estimate.
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